Well, that is the reason as to why game studios exist, i.e. more people will be able to divide the work and create more (and larger) games by working together.
I think that you missed the crucial point here. I would argue that everyone on these forums who is developing games is doing so for one of two reasons (or both) and those are: creating games because it is challenging and fun, or creating games in order to make money.
Now, if you are just creating games for a challenge and the fun of it and no money is involved, then you might think that you don’t require any contracts. I have been a part of a few such projects where no such contracts were made, because we all knew that we’d get things done, the game would be great, etc. you name it. However, during the development, some disagreements are bound to rise and you need to ask yourself: who has the final say? What if the other team members don’t like that decision? What if people just get bored of the project or their lives take them elsewhere, like school, another job, etc.? Will they just leave and if they do leave, then what happens to the project? Can you and the remaining team members finish it within reason? Do those who left own any part of the project or is their stake forfeited? Without legally enforceable contracts, you may (and will) run into trouble at some point.
In the hopeful case that the end game is completed, then who has the responsibility of releasing it and paying the associated fees? If the game is really 100% free and won’t ever generate a cent of revenue, then this’ll probably be easier. But, if the game does intend to include some purchases, pay to download fee or ads, then you are talking about setting up a company and paying the team members somehow, for which you require contracts. You’d also run into the issues of who owns the rights to the IP, i.e. can every team member use the code, name, assets, etc. for future projects and do they need to involve others, etc.
Take the two of us, for instance. One of my, and I presume everyone else’s favourite things about game development, is the design part. So, we’d both want to do that. Then, if I’d do most or all of the programming, we’d be left with marketing, visuals and other assets, etc. I have varying degrees of experience in all of the aforementioned fields through academic study and years of consulting, web and graphic design and game development. Now, I wouldn’t be interested in just creating games for fun, even though it is a lot of fun. Then we’d be left with two alternatives: we’d share the potential future profits of our games or one of us hires the other to work on the game. The idea of sharing unknown and uncertain future profits doesn’t interest me as I have my own projects that offer that, plus I’d have to only pay my existing team for their work and I retain the creative freedom. Now, if you’d want to hire me for projects, that’d be fine as then I would be paid to do what I love and I wouldn’t have to take any risks or worry about the possible future profits or other issues, because everything would be detailed in my contract.
Now, I don’t know how old you are, or what your level of experience is, but you sound a bit like I did when I was starting out, i.e. naive. You will probably be burned a few times on group/team projects, like I have, and afterwards you’ll start to understand my point-of-view.
Now everything is fixed and the game actually runs on all phones and tablets. Oh, and I also adjusted the difficulty a bit.